1. Field of the Invention
The present invention relates to a thin film magnetic head having at least an inductive magnetic transducer for recording, a method of manufacturing the same, and a magnetic recording apparatus in which a thin film magnetic head is mounted.
2. Description of the Related Art
In recent years, in association with improvement in areal density of a magnetic recording medium (hereinbelow, simply called “recording medium”) such as a hard disk, improvement in the performance of a thin film magnetic head to be mounted on a magnetic recording apparatus such as a hard disk drive (HDD) is demanded. Examples of known recording methods of a thin film magnetic head are a longitudinal recording method in which the orientation of a signal magnetic field is set to an in-plane direction (longitudinal direction) of a recording medium and a perpendicular recording method in which the orientation of a signal magnetic field is set to a direction orthogonal to the surface of a recording medium. At present, the longitudinal recording method is widely used. However, when a market trend accompanying improvement in areal density of a recording medium is considered, it is assumed that, in place of the longitudinal recording method, the perpendicular recording method will be regarded as a promising method in future for the following reason. The perpendicular recording method has advantages such that high linear recording density can be assured and a recorded recording medium is not easily influenced by thermal decay.
A thin film magnetic head of the perpendicular recording method has, mainly, a thin film coil for generating a magnetic flux for recording and a magnetic pole layer extending rearward from an air bearing surface and generating a magnetic field (perpendicular magnetic field) for magnetizing a recording medium on the basis of the magnetic flux generated by the thin film coil. In the thin film magnetic head of the perpendicular recording method, the recording medium is magnetized by the perpendicular magnetic field generated in the magnetic pole layer and information is magnetically recorded on the recording medium.
Some modes of the structure of the thin film magnetic head in the perpendicular recording method have already been proposed. Concretely, for example, there is a known main magnetic pole (magnetic multilayer film) constructed so as to have a stacked structure in which a high-saturation magnetic flux density layer and a low-saturation magnetic flux density layer are alternately stacked to prevent recorded information from being erased after recording by suppressing occurrence of a residual magnetic field right after recording operation (refer to, for example, Japanese Patent Laid-open No. 2004-281023). In the thin film magnetic head of perpendicular recording method having the main magnetic pole of this kind, the main magnetic pole has a return magnetic domain structure so that occurrence of residual magnetization is suppressed. Consequently, the residual magnetic field is not easily generated right after recording operation and erasure after recording dose not easily occur.